Vernier TI Light Probe User manual

TI Light Probe

(Order Code TILT-BTA)

The TI Light Probe is an inexpensive light sensor that uses a phototransistor to

measure irradiance, the measure of electromagnetic power per unit area. The sensor

is best used for relative or comparative measurements. The sensor’s spectral

response is between 300 nm and 1100 nm so it measures UV, visible, and infrared

light. The infrared capabilities of the sensor allow it to be used for investigations

outside the visible spectrum. An excellent example of an appropriate use of this

sensor would be to compare the reflectivity of different surfaces. In this type of

experiment, you are looking for relative changes in reflected light from different

surfaces rather than an absolute value. Other typical uses of the TI Light Probe

include:

 investigating the inverse square law of light

 measuring the flicker of fluorescent lights

 measuring changes in light intensity for crossed polarizers

 investigating the refresh rate of a television or CRT computer monitor

 studying IR signals from remote controls for TVs, VCRs, DVDs, etc.

The range of the sensor is between approximately 10 µW/cm

and 1 mW/cm

. The

maximum reading is equivalent to a 100 W light bulb placed at a distance of

approximately 0.5 m from the sensor; therefore, the sensor cannot be used to

measure the sun’s irradiance.

The accuracy of the sensor is 20%. This variation in accuracy affects the types of

uses for this sensor. The lack of sensor accuracy is a drawback in experiments that

require accuracy. For example, you might be interested in measuring the light output

of a small DC lamp and comparing it to the electrical energy power used by the DC

lamp. In such an experiment, accuracy would be important and another sensor would

be more appropriate.

Most Vernier data-collection programs do not assign a unit to

the sensor measurement since the sensor is used for relative measurements. Instead

the unit is omitted, and it is understood that the reading is a relative measurement.

Vernier Software & Technology

13979 S.W. Millikan Way  Beaverton, OR 97005-2886

Toll Free (888) 837-6437  (503) 277-2299  FAX (503) 277-2440

[email protected]  www.vernier.com

Rev. 6/18/12

Vernier Light Sensor (order code LS-BTA) is a more accurate light sensor. It measures visible light. It can be used to

measure light intensity of the sun.